遙地相關與台灣地區冬春季月雨量年際變化

Teleconnections and Interannual Variations of Winter and Spring Monthly Rainfall in Taiwan

蔡清彥(Ching-Yen Tsay)

《大氣科學》 13卷1期 (1986/03) Pp. 21-32

摘要

本文利用27年資料，分析台灣地區每個月之月雨量年際變化，以及其與北半球各網格點上500 mb高度場之相關係數，得到北半球關係數圖。然後求取遙地相關指數，計算指數正值最大6年的北半球合成平均圖、負值最大6年的合成圖、以及前者減去後者之合成差異圖。此差異圖大致上可代表多雨年與少雨年之差異圖。分析這些合成圖，我們得到各季節之遙地相關特性。500 mb合成差異圖在十二月及一月份，東半球及西半球均屬於負PNA遙地相關型式（Wallace and Gutzler，1981）。在二月份，北美洲及整個太平洋地區均屬於正PNA型式，但在0°至90°E之間各屬於負PNA型式。在三月份，東半球及西半球均屬於正PNA型式。在四月份，北美洲及整個太平洋地區仍屬於正PNA型式，而在歐亞大陸地區差值很小。

並列摘要

This paper studies interannual variations of monthly rainfall amounts in Taiwan, and their correlations with 500 mb height fields at grid points in northern hemisphere. Teleconnection indices as well as Composite northern-hemisphere 500 mb maps for the 6 month out of 27 month data with strongest positive and negative teleconnection indices are calculated. After analyzing these composite maps, we are able to find teleconnection characteristics for various time periods in a year.The 500 mb difference map, computed by subtracting the compos it e map with negative index from that with positive index, has very interesting characteristics is December through April next year. In December and January, both east and west portions of northern-hemisphere belong to negative PNA pattern (Wallace an d Gutzler, 1981). In February, north American Continent as well as the whole north Pacific belong to positive PNA pattern, but the area from 0° to 90°E belongs to negative PNA pattern. In March, both east and west portions of northern hemisphere belong to positive PNA pattern. In April, north American continent as well as the whole north Pacific belong to positive PNA pattern, but the difference values are small in Eurasian Continent.